The Effectiveness of Vertical Perspective and Pursuit Eye Movements for Disambiguating Motion Parallax Transformations.

In the kinetic depth effect, the direction of the perceived depth and the direction of apparent rotation of a 3-D structure are linked, and typically ambiguous, whereas depth from motion parallax during both observer- and object-movement is stable and unambiguous. Rogers and Rogers demonstrated that the vertical perspective transformations play an important role in disambiguating the direction of the perceived depth in parallax-defined surfaces but more recently Nawrot et al. have proposed that pursuit eye movements provide the crucial disambiguating information. Theoretical considerations suggest that pursuit eye movements could not, in principle, provide the necessary information because 3-D objects as surfaces may rotate during observer- or object-movement. The empirical evidence presented here shows that vertical perspective transformations are sufficient for the unambiguous perception of parallax depth whereas pursuit eye movements are not necessary and may not even be sufficient.